U.S. patent number 7,847,824 [Application Number 12/046,668] was granted by the patent office on 2010-12-07 for shake correction apparatus of a camera.
This patent grant is currently assigned to Hoya Corporation. Invention is credited to Makoto Mogamiya.
United States Patent |
7,847,824 |
Mogamiya |
December 7, 2010 |
Shake correction apparatus of a camera
Abstract
A shake correction apparatus of a camera, includes a stationary
support board; an electrical board movable relative to the
stationary support board; an image pickup device supported by the
electrical board and including leads made of a magnetic material
which are arranged on a periphery of the image pickup device to
electrically connect the image pickup device to the electrical
board; at least one drive coil which moves with the electrical
board; at least one magnet provided on a surface of the stationary
support board which faces the electrical board, and positioned
around the image pickup device and the leads as viewed from the
front thereof, the magnet exerting a magnetic force on the drive
coil; and at least one magnetic cover, made of a magnetic
substance, for covering a portion of the magnet which faces the
leads.
Inventors: |
Mogamiya; Makoto (Tokyo,
JP) |
Assignee: |
Hoya Corporation (Tokyo,
JP)
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Family
ID: |
39762251 |
Appl.
No.: |
12/046,668 |
Filed: |
March 12, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080225126 A1 |
Sep 18, 2008 |
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Foreign Application Priority Data
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Mar 14, 2007 [JP] |
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2007-064394 |
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Current U.S.
Class: |
348/208.7;
396/54; 310/12.05; 348/208.4 |
Current CPC
Class: |
H04N
5/2253 (20130101); H04N 5/23248 (20130101) |
Current International
Class: |
H04N
5/228 (20060101); G03B 17/00 (20060101); H02K
41/02 (20060101) |
Field of
Search: |
;348/208.99,208.2,208.4,208.5,208.7 ;396/52,54,55
;310/12.05,12.06 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2006-108956 |
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Apr 2006 |
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JP |
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2007-025180 |
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Feb 2007 |
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JP |
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2007-025616 |
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Feb 2007 |
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JP |
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Other References
English language Abstract of JP 2006-108956. cited by other .
English language Abstract of JP 2007-025180. cited by other .
English language Abstract of JP 2007-025616. cited by other .
U.S. Appl. No. 11/961,037 to Mogamiya, which was filed on Dec. 20,
2007. cited by other.
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Primary Examiner: Tran; Sinh
Assistant Examiner: Pasiewicz; Daniel M
Attorney, Agent or Firm: Greenblum & Bernstein,
P.L.C.
Claims
What is claimed is:
1. A shake correction apparatus of a camera, comprising: a
stationary support board; an electrical board movable relative to
said stationary support board; an image pickup device supported by
said electrical board and including leads made of a magnetic
material which are arranged on a periphery of said image pickup
device to electrically connect said image pickup device to the
electrical board; at least one drive coil which is mounted on said
electrical board positioned around said image pickup device and
said leads; at least one magnet provided on said stationary support
board which faces said drive coil, said magnet exerting a magnetic
force on said drive coil; and at least one magnetic cover, made of
a magnetic substance, for covering a portion of said magnet which
faces said leads.
2. The shake correction apparatus according to claim 1, wherein
said magnetic cover comprises a magnetic sheath made from a
magnetic material and is fixed to said stationary support
board.
3. The shake correction apparatus according to claim 1, wherein
said magnetic cover comprises a magnetic substance which is coated
on said magnet.
4. The shake correction apparatus according to claim 1, wherein
said magnetic cover covers an outer peripheral surface of said
magnet.
5. The shake correction apparatus according to claim 1, wherein
said magnet comprises at least one X-direction magnet and at least
one Y-direction magnet, and wherein said drive coil comprises: at
least one X-direction drive coil which generates a driving force
for moving said electrical board in an X-direction as a specific
linear direction upon being supplied with an electric current in a
state where said X-direction drive coil receives a magnetic force
exerted by said X-direction magnet; and at least one Y-direction
drive coil which generates a driving force for moving said
electrical board in a Y-direction orthogonal to said X-direction
upon being supplied with an electric current in a state where said
Y-direction drive coil receives a magnetic force exerted by said
Y-direction magnet.
6. The shake correction apparatus according to claim 1, wherein
said stationary support board comprises a front stationary support
board and a rear stationary support board which are substantially
parallel to each other, wherein said electrical board is positioned
between said front stationary support board and said rear
stationary support board, and wherein said shake correction
apparatus further comprises: a stage plate which moves with said
electrical board and includes at least three support holes formed
as through-holes; and at least three balls engaged in said support
holes to be allowed to rotate therein, respectively, said balls
being capable of making contact with said front stationary support
board and said rear stationary support board, wherein diameters of
said balls are smaller than a distance between opposed surfaces of
said front stationary support board and said rear stationary
support board.
7. The shake correction apparatus according to claim 5, further
comprising: a gyro sensor for detecting deflections of said camera;
and a controller which operates to pass current through said
X-direction drive coil and said Y-direction drive coil to move said
stage member in a manner to compensate camera shake in accordance
with information on said deflections detected by said gyro
sensor.
8. The shake correction apparatus according to claim 1, wherein at
least one side surface of said magnet which faces said camera body
is covered by said magnetic cover.
9. The shake correction apparatus according to claim 1, wherein
said magnet comprises at least two pairs of magnets, and wherein
said magnetic cover comprises at least two magnetic covers which
surround said two pairs of magnets, respectively.
10. The shake correction apparatus according to claim 1, wherein
said drive coil is made as a flat coil lying in a plane parallel to
a plane in which said electrical board is movable.
11. The shake correction apparatus according to claim 6, wherein
said electrical board is fixed to a back of said stage plate with
said image pickup device projecting forward from said stage plate
through a hole formed in a center of said stage plate.
12. The shake correction apparatus according to claim 1, wherein
said stationary support board comprises a front stationary support
board and a rear stationary support board which are substantially
parallel to each other, wherein said electrical board is positioned
between said front stationary support board and said rear
stationary support board, wherein said shake correction apparatus
further comprises: a stage plate which moves with said electrical
board and includes at least three support holes formed as
through-holes; at least three balls engaged in said support holes
to be allowed to rotate therein, respectively; and at least three
retainers fixedly fitted into at least three through-holes formed
in said front stationary support board, said balls being positioned
between said rear stationary support board and rear end surfaces of
said retainers, respectively.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shake correction apparatus of a
camera.
2. Description of the Prior Art
Shake correction apparatuses (shake reduction systems/image
stabilizers) for use in cameras using an image pickup device as an
imaging sensor are usually provided with a first stationary support
plate fixed to an internal surface of a camera body, a second
stationary support plate substantially parallel to the first
stationary support plate, and a stage plate positioned between the
first and second stationary support plates. The front of the stage
plate supports the image pickup device via an electrical board, and
the stage plate can move relative to the first and second
stationary support plates while maintaining a substantially
parallel state relative to the first and second stationary support
plates. Additionally, a plurality of stage-member-driving magnets
are fixed to a surface of the first stationary support plate which
faces the stage plate, while a plurality of drive coils are fixed
to a flexible PCB (printed circuit board) integral with the stage
plate so as to face the plurality of stage-member-driving magnets
in the forward/rearward direction of the camera, respectively.
In this type of shake correction apparatus, passing currents
through the drive coils at the occurrence of camera shake caused by
hand shake causes each drive coil, through which a current is
passed, to produce a driving force for moving the electrical board
and the image pickup device. Thereupon, the image pickup device
moves in directions to offset the camera shake to thereby correct
image shake of an image captured by the image pickup device.
An example of this type of shake correction apparatus of a camera
is disclosed in Japanese unexamined patent publication
2006-108956.
When the stage plate to which the image pickup device is mounted is
driven to move slidingly through the use of magnetic forces
produced by magnets, the following problem occurs. Namely, a great
number of leads (signal wires) made of a magnetic material are
installed in the periphery of the image pickup device and are
electrically connected to an electrical board. However, the leads
are bare and therefore may be influenced by magnetic forces
produced by the magnets. Accordingly, if the leads are influenced
by the magnetic forces, the stage plate (the leads) are attracted
toward the magnets thereby, which causes some trouble in the
shake-correction performance of the stage plate.
SUMMARY OF THE INVENTION
The present invention provides a shake correction apparatus of a
camera which is configured to prevent the leads from being subject
to the influence of magnetic forces produced by magnets in an
effective manner.
According to an aspect of the present invention, a shake correction
apparatus of a camera is provided, including a stationary support
board; an electrical board movable relative to the stationary
support board; an image pickup device supported by the electrical
board and including leads made of a magnetic material which are
arranged on a periphery of the image pickup device to electrically
connect the image pickup device to the electrical board; at least
one drive coil which is mounted on the electrical board positioned
around the image pickup device and the leads; at least one magnet
provided on the stationary support board which faces the drive
coil, the magnet exerting a magnetic force on the drive coil; and
at least one magnetic cover, made of a magnetic substance, for
covering a portion of the magnet which faces the leads.
Accordingly, a magnetic force produced by the magnet can be
prevented from exerting an adverse influence on the leads of the
image pickup device in an effective manner because a portion of the
magnet which faces the leads is covered by a magnetic cover.
Accordingly, the leads of the image pickup device in the shake
correction device according to the present invention are less
subject to magnetic force than those of a conventional shake
correction device having a image pickup device, so that the
electrical board can move without hindrance.
It is desirable for the magnetic cover to be a magnetic sheath made
from a magnetic material and be fixed to the stationary support
board.
It is desirable for the magnetic cover to be a magnetic substance
which is coated on the magnet.
It is desirable for the magnetic cover to cover an outer peripheral
surface of the magnet. Accordingly, a magnetic force produced by
the magnet can be prevented from exerting a bad influence on the
leads of the image pickup device in a more effective manner.
It is desirable for the magnet to include at least one X-direction
magnet and at least one Y-direction magnet, and for the drive coil
to include at least one X-direction drive coil which generates a
driving force for moving the electrical board in an X-direction as
a specific linear direction upon being supplied with an electric
current in a state where the X-direction drive coil receives a
magnetic force exerted by the X-direction magnet; and at least one
Y-direction drive coil which generates a driving force for moving
the electrical board in a Y-direction orthogonal to the X-direction
upon being supplied with an electric current in a state where the
Y-direction drive coil receives a magnetic force exerted by the
Y-direction magnet.
Accordingly, the electrical board and the image pickup device can
be driven so as to move in the X-direction and the Y-direction
through the use of magnetic force.
It is desirable for the stationary support board to include a front
stationary support board and a rear stationary support board which
are substantially parallel to each other. The electrical board is
positioned between the front stationary support board and the rear
stationary support board. The shake correction apparatus further
includes a stage plate which moves with the electrical board and
includes at least three support holes formed as through-holes; and
at least three balls engaged in the support holes to be allowed to
rotate therein, respectively, the balls being capable of making
contact with the front stationary support board and the rear
stationary support board, wherein diameters of the balls are
smaller than a distance between opposed surfaces of the front
stationary support board and the rear stationary support board.
Accordingly, the electrical board can not only move linearly in the
X-direction and the Y-direction relative to the front stationary
support board and the rear stationary support board but also rotate
in an X-Y axis plane that is substantially parallel to both the
X-direction and the Y-direction since at least three balls, which
are respectively engaged in the support holes to be allowed to
rotate therein, respectively, make contact with the front
stationary support board or the rear stationary support board
(i.e., each ball does not make contact with the front and rear
stationary support boards simultaneously). Accordingly, the shake
correction apparatus can also offset so-called rotational image
shake.
It is desirable for the shake correction apparatus to include a
gyro sensor for detecting deflections of the camera; and a
controller which operates to pass current through the X-direction
drive coil and the Y-direction drive coil to move the stage member
in a manner to compensate camera shake in accordance with
information on the deflections detected by the gyro sensor.
Accordingly, a precise shake correcting operation of the shake
correction apparatus can be achieved.
It is desirable for at least one side surface of the magnet which
faces the camera body to be covered by the magnetic cover.
Accordingly, a magnetic force produced by the magnet does not
easily reach a portion of the camera body which faces the magnet
from a portion of the magnet which faces the camera body.
Therefore, even if an object made of a magnetic substance comes
near to the outer surface of the portion of the camera body that
faces the portion of the magnet, the object is prevented from being
magnetically attracted to the camera body in an effective
manner.
It is desirable for the magnet to include at least two pairs of
magnets, and for the magnetic cover to include at least two
magnetic covers which surround the two pairs of magnets,
respectively.
It is desirable for the drive coil to be made as a flat coil lying
in a plane parallel to a plane in which the electrical board is
movable.
It is desirable for the electrical board to be fixed to a back of
the stage plate with the image pickup device projecting forward
from the stage plate through a hole formed in a center of the stage
plate.
It is desirable for the stationary support board to include a front
stationary support board and a rear stationary support board which
are substantially parallel to each other. The electrical board is
positioned between the front stationary support board and the rear
stationary support board. The shake correction apparatus further
includes a stage plate which moves with the electrical board and
includes at least three support holes formed as through-holes; at
least three balls engaged in the support holes to be allowed to
rotate therein, respectively; and at least three retainers fixedly
fitted into at least three through-holes formed in the front
stationary support board, the balls being positioned between the
rear stationary support board and rear end surfaces of the
retainers, respectively.
The present disclosure relates to subject matter contained in
Japanese Patent Application No. 2007-64394 (filed on Mar. 14, 2007)
which is expressly incorporated herein in its entirety.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be discussed below in detail with
reference to the accompanying drawings, in which:
FIG. 1 is a longitudinal sectional view of a digital camera having
a shake correcting function;
FIG. 2 is a front perspective view of the shake correction
apparatus;
FIG. 3 is a rear perspective view of the shake correction
apparatus;
FIG. 4 is an exploded front perspective view of the shake
correction apparatus;
FIG. 5 is an exploded rear perspective view of the shake correction
apparatus;
FIG. 6 is a front elevational view of the shake correction
apparatus;
FIG. 7 is a rear elevational view of a front stationary support
plate of the shake correction apparatus, and associated elements
mounted to the front stationary support plate;
FIG. 8 is a front perspective view of an image pickup device shown
in FIGS. 4 and 6;
FIG. 9 is a cross sectional view taken along the XI-XI arrows shown
in FIG. 6; and
FIG. 10 is a rear elevational view of the shake correction
apparatus with both a rear stationary support plate and a flexible
PCB being removed for clarity.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of a shake correction apparatus (image
stabilizer/shake reduction system) 20 according to the present
invention which is incorporated in a digital camera 10 will be
hereinafter discussed with reference to the accompanying drawings.
In the following description, the horizontal direction, the
vertical direction and the front-back direction of the shake
correction apparatus 20 of the digital camera 10 are referred to as
an X-direction, a Y-direction and a Z-direction, respectively, as
shown by the double-headed arrows shown in FIGS. 1 and 10.
Firstly, the basic structures of the digital camera 10 and the
shake correction apparatus 20 will be discussed hereinafter.
As shown in FIG. 1, a lens barrel 11 of the digital camera 10 is
provided therein with a photographing optical system including a
plurality of lenses L1, L2 and L3, and is provided, in a camera
body 12 behind the rearmost lens L3, with the shake correction
apparatus 20.
As shown in FIGS. 2 through 10, the shake correction apparatus 20
is provided with a front stationary support board (stationary
support board) 21 and a rear stationary support board (stationary
support board) 22. The front stationary support board 21 is in the
shape of a horizontally-elongated rectangle as viewed from the
front and is made of a magnetic material such as a soft metal. The
rear stationary support board 22 has approximately the same shape
and size as the front stationary support board 21 and is also made
of a magnetic material such as a soft metal. The front stationary
support board 21 is provided, at five different positions on the
rear surface thereof, with five connecting columns 23,
respectively, which project rearward, and each of the five
connecting columns 23 is provided at the rear end surface thereof
with a female screw hole 24. The rear stationary support board 22
is provided, at five different position thereon which correspond to
the positions of the five connecting columns 23, with five
through-holes 25, respectively. As shown in FIG. 9, five set screws
26 (only one of which is shown in FIG. 9), each having a male screw
thread portion 27, are inserted into the five through-holes 25, and
the male screw thread portions 27 of the five set screws 26 are
screwed into the female screw holes 24 of the five connecting
columns 23, respectively. Due to the screw engagements of the five
set screws 26 with the five connecting columns 23, the front
stationary support board 21 and the rear stationary support board
22 are connected so as to be parallel to each other.
The front stationary support board 21 is provided in a central
portion thereof with a rectangular hole 28. Likewise, the rear
stationary support board 22 is provided in a central portion
thereof with a rectangular hole 29. The shake correction apparatus
20 is provided with a lower-end connecting member 30 having an
L-shaped cross section which is connected to the front stationary
support board 21 so as to cover along the lower ends of the front
stationary support board 21 and the rear stationary support board
22. Furthermore, the rear stationary support board 22 is connected
to an internal surface of the camera body 12 by three set screws
(not shown).
The front stationary support board 21 is provided, at two different
positions thereon in the vicinity of the right and left upper
corners of the front stationary support board 21 with two fitting
holes (through-holes) 31, respectively. The front stationary
support board 21 is further provided, at a position thereon in the
vicinity of a center of the front stationary support board 21 in
the X-direction, with a fitting hole (through-hole) 31 (see FIG.
9). Each fitting hole 31 is circular as viewed from the front.
Three retainers 32 are fixedly fitted into the three fitting holes
31 from the back of the front stationary support board 21,
respectively (each retainer 32 serves as a part of the front
stationary support board 21). The rear ends of the three retainers
32 are formed as large-diameter retaining portions 33 which are
greater in diameter than the three fitting holes 31, respectively.
The retaining portions 33 are in contact with the back of the front
stationary support board 21. Accordingly, the retaining portions 33
of the three retainers 32 do not come out of the three fitting
holes 31 from the front thereof, respectively. Additionally, the
rear end surfaces of the retaining portions 33 are formed as
contacting flat surfaces 34 which are parallel to both the front
stationary support board 21 and the rear stationary support board
22.
The shake correction apparatus 20 is provided, on the rear surface
of the front stationary support board 21 on the horizontally
opposite sides of the rectangular hole 28, with two (right and
left) pairs of X-direction magnets MX made of permanent magnets,
respectively. The rear half of the left X-direction magnet MX
serves as an S-pole and the front half of the left X-direction
magnet MX serves as an N-pole, as viewed in FIGS. 5, 7 and 10 (the
front half and the rear half of the right magnet as viewed from the
front of the shake correction apparatus 20). Similarly, the rear
half of the right X-direction magnet MX serves as an N-pole and the
front half of the right X-direction magnet MX serves as an S-pole,
as viewed in FIGS. 5, 7 and 10 (the front half and the rear half of
the left magnet as viewed from the front of the shake correction
apparatus 20). The right and left pairs of X-direction magnets MX
are aligned in the X-direction, and the positions of the right and
left pairs of X-direction magnets MX in the Y-direction are the
same. The paths of magnetic flux of the right and left pairs of
X-direction magnets MX through the front stationary support board
21 and the rear stationary support board 22 form two X-direction
magnetic circuits between the two X-direction magnets MX and two
portions of the rear stationary support board 22 which face the two
X-direction magnets MX in the Z-direction, respectively.
The shake correction apparatus 20 is further provided, on the rear
surface of the front stationary support board 21 below the
rectangular hole 28, with two (upper and lower) pairs of
Y-direction magnets MYA and MYB made of permanent magnets which are
arranged side by side in the horizontal direction, i.e., the
X-direction. In each pair of Y-direction magnets MYA and MYB, the
rear half of the upper magnet serves as an N-pole and the front
half of the upper magnet serves as an S-pole, as viewed in FIGS. 5,
7 and 11, and the rear half of the lower magnet serves as an S-pole
and the front half of the lower magnet serves as an N-pole, as
viewed in FIGS. 5, 7 and 11. The paths of magnetic flux of the
right and left pairs of Y-direction magnets MYA and MYB through the
front stationary support board 21 and the rear stationary support
board 22 form two Y-direction magnetic circuits between the two
Y-direction magnets MYA and MYB and two portions of the rear
stationary support board 22 which face the two Y-direction magnets
MYA and MYB in the Z-direction, respectively.
Accordingly, the front stationary support board 21 and the rear
stationary support board 22 function as yokes.
The shake correction apparatus 20 is provided on the periphery of
each pair of X-direction magnets MX with a magnetic sheath
(magnetic cover) 35 made of a magnetic material such as metal which
is in the shape of a rectangle as viewed from the front of the
shake correction apparatus 20, and the inner peripheral surface of
each magnetic sheath 35 is fixed to peripheral surfaces (outer
edges) of the associated pair of X-direction magnets MX. Likewise,
the shake correction apparatus 20 is provided on the periphery of
the left pair of Y-direction magnet MYA with a magnetic sheath
(magnetic cover) 36 made of a magnetic material such as metal which
is in the shape of a rectangle as viewed from the front of the
shake correction apparatus 20, and the inner peripheral surface of
the magnetic sheath 36 is fixed to peripheral surfaces (outer
edges) of the pair of Y-direction magnets MYA. Likewise, the shake
correction apparatus 20 is provided on the periphery of the right
pair of Y-direction magnets MYB with a magnetic sheath (magnetic
cover) 37 made of a magnetic material such as metal which is in the
shape of a rectangle as viewed from the front of the shake
correction apparatus 20, and the inner peripheral surface of the
magnetic sheath 37 is fixed to peripheral surfaces (outer edges) of
the pair of Y-direction magnets MYB. The front surfaces of all the
four magnetic sheaths 35, 36 and 37 are fixed to the back of the
front stationary support board 21.
The shake correction apparatus 20 is provided between the front
stationary support board 21 and the rear stationary support board
22 with a stage plate 40. The stage plate 40 is provided in the
upper right corner and the upper left corner thereof with two
moving range limit holes 41, respectively, and is further provided,
at the lower end of the stage plate 40 at the center in the
horizontal direction, with one moving range limit hole 41. Each of
the three moving range limit holes 41 is substantially rectangular
in shape. As shown in FIG. 10, two of the five connecting columns
23 which project from the front stationary support board 21 in the
vicinity of the right and left upper corners thereof pass through
the aforementioned two moving range limit holes 41 of the stage
plate 40 in the Z-direction, respectively, while one of the five
connecting columns 23 which projects from the lower end of the
front stationary support board 21 at the horizontal center thereof
passes through the aforementioned one moving range limit recess 41
of the stage plate 40 in the Z-direction.
The stage plate 40 is provided, at three different positions
thereon which face the three retainers 32 (the contacting flat
surfaces 34) in the Z-direction, with three support holes
(through-holes) 42, respectively, each of which is circular in
shape as viewed from the front. Three balls B are inserted into the
three support holes 42 to be rotatable therein, respectively. The
diameters of the three balls B are slightly smaller than the
distance between the contacting flat surfaces 34 and the surface of
the rear stationary support board 22 which face the contacting flat
surfaces 34 in the Z-direction; and accordingly, each ball B does
not come into contact with the contacting flat surface 34 of the
associated retainer 32 and the front surface of the rear stationary
support board 22, which is parallel to the contacting flat surface
34, simultaneously.
Since the three balls B are in contact with the contacting flat
surfaces 34 of the three retainers 32 and the front surface of the
rear stationary support board 22 in this manner, the stage plate 40
can not only move linearly in the X-direction and the Y-direction
relative to the front stationary support board 21 and the rear
stationary support board 22 but also rotate in an X-Y axis plane
that is parallel to both the X-direction and the Y-direction (i.e.,
that is orthogonal to the optical axis O) from the initial position
of the stage plate 40 that is shown in FIG. 10.
Additionally, since three of the five connecting columns 23 that
project from the front stationary support board 21 are loosely
engaged in the three moving range limit holes 41 of the stage plate
40, respectively, the range of sliding movement of the stage plate
40 and an electrical board 45 (on which an image pickup device 44
is mounted) is limited by the three connecting columns 23 and the
three moving range limit holes 41.
The stage plate 40 is provided in the center thereof with an
image-pickup-device mounting hole 43 formed as a through-hole that
is rectangular in shape as viewed from the front (see FIG. 9). As
shown in FIG. 9, the image pickup device 44 is fixed to the
electrical board 45 on a central portion of the front surface
thereof, and the electrical board 45 is fixed to the back of the
stage plate 40 with the image pickup device 44 projecting forward
from the stage plate 40 through the image-pickup-device mounting
hole 43. The stage plate 40 and the electrical board 45 that is
fixed to the back of the stage plate 40 serves as a movable stage
which is integral with the image pickup device 44.
As shown in FIG. 8, the image pickup device 44 is provided on the
front thereof with an imaging surface 46. In addition, the image
pickup device 44 is provided around the imaging surface 46 with a
large number of leads (signal lines) 47 which project rearward from
the outer edge of the image pickup device 44.
The imaging surface 46 of the image pickup device 44 is an
image-forming surface on which object light which is passed through
the lenses L1, L2 and L3 is formed as an object image. When the
stage plate 40 is in the initial position (when the stage plate 40
is in the state shown in FIG. 10), the center of the imaging
surface 46 of the image pickup device 44 is positioned on an
optical axis O of the lenses L1, L2 and L3. As shown in FIG. 10,
the image pickup device 44 is provided with a pair of X-direction
edges (upper and lower X-direction edges) 44X which extend parallel
to each other in the X-direction and a pair of Y-direction edges
(right and left Y-direction edges) 44Y which extend parallel to
each other in the Y-direction when the stage plate 40 is in the
position (initial position) shown in FIG. 10.
The leads 47 of the image pickup device 44 that serve as
imaging-signal transmission devices are made of a magnetic
material. The leads 47 project rearward from the electrical board
45 through a corresponding number of through-holes (not shown)
formed in the electrical board 45, respectively. Each lead 47 is
electrically connected to an electrical circuit (not shown) and a
flexible printed circuit board FPC. As shown in FIGS. 9 and 10, the
three magnetic sheaths 35, 36 and 37 are positioned around the
image pickup device 44 (i.e., around the leads 47). More
specifically, the two magnetic sheaths 35 are positioned on the
horizontally opposite sides of the image pickup device 44, while
the two magnetic sheaths 36 and 37 are positioned below the image
pickup device 44.
The flexible printed circuit board FPC which is shaped to be
prevented from interfering with the electrical board 45 is fixed to
the back of the stage plate 40. The flexible printed circuit board
FPC is electrically connected to a controller C (see FIG. 1) which
is constructed from a CPU or the like incorporated in the camera
body 12.
As shown in FIG. 10, the stage plate 40 is provided on the
horizontally opposite sides of the image pickup device 44 with a
pair of coil mounting holes (through-holes) 50 that are vertically
elongated, respectively, and is further provided below the image
pickup device 44 with a pair of (right and left) coil mounting
holes (through-holes) 51 that are horizontally-elongated.
Two X-direction drive coils (flat coils/drive coils) CX having the
same specifications are fixedly mounted on the front surface of the
flexible printed circuit board FPC at the horizontally opposite
ends of the stage plate 40 and fitted in the pair of coil mounting
holes 50, respectively. The two X-direction drive coils CX lie in a
plane parallel to an X-Y axis plane and are aligned in a direction
parallel to the pair of X-direction edges 44X of the image pickup
device 44 (i.e., in the X-direction in the state shown in FIG. 10).
In other words, the positions of the two X-direction drive coils CX
in the direction parallel to the pair of Y-direction edges 44Y (in
the Y-direction in the state shown in FIG. 10) are coincident with
each other. Each X-direction drive coil CX is rectangularly coiled
(both in the direction parallel to the stage plate 40 and in the
direction of thickness of the stage plate 40) to have over one
hundred turns. The two X-direction drive coils CX are positioned to
correspond to the aforementioned two X-direction magnetic circuits
(the front stationary support board 21, the rear stationary support
board 22 and the two X-direction magnets MX), respectively. In
other words, the two X-direction drive coils CX are positioned to
face the two X-direction magnets MX in the Z-direction,
respectively.
Two Y-direction drive coils (flat coils/drive coils) CYA and CYB
having the same specifications are fixedly mounted on the front
surface of the flexible printed circuit board FPC at the lower end
of the stage plate 40 and fitted in the pair of coil mounting holes
51, respectively. The two Y-direction drive coils CYA and CYB lie
in a plane parallel to an X-Y axis plane and are aligned in a
direction parallel to the pair of X-direction edges 44X of the
image pickup device 44 (in the X-direction in the state shown in
FIG. 10). In other words, the positions of the two Y-direction
drive coils CYA and CYB in the direction parallel to the pair of
Y-direction edges 44Y (in the Y-direction in the state shown in
FIG. 10) are coincident with each other. Each Y-direction drive
coil CYA and CYB is rectangularly coiled (both in the direction
parallel to the stage plate 40 and in the direction of thickness of
the stage plate 40) to have over one hundred turns. The two
Y-direction drive coils CYA and CYB are positioned to correspond to
the aforementioned two Y-direction magnetic circuits (the front
stationary support board 21, the rear stationary support board 22
and the two Y-direction magnets MY), respectively. In other words,
the two Y-direction drive coils CYA and CYB are positioned to face
the two Y-direction magnets MY in the Z-direction,
respectively.
Additionally, as shown in FIG. 10, an X-direction Hall element HX
(see FIG. 10) is fixed to the front surface of the flexible printed
circuit board FPC to be positioned inside the left X-direction
drive coil CX, and two Y-direction Hall elements HY are fixed to
the front surface of the flexible printed circuit board FPC to be
positioned inside the two Y-direction drive coils CYA and CYB,
respectively.
The two X-direction drive coils CX, the two Y-direction drive coils
CYA and CYB, the X-direction Hall element HX and the two
Y-direction Hall elements HY are all electrically connected to the
controller C (incorporated in the camera body 12) via the flexible
printed circuit board FPC.
The shake correction apparatus 20 carries out a shake correction
operation (image stabilizing operation) so as to offset image shake
by passing currents through the two X-direction drive coils CX and
the two Y-direction drive coil CYA and CYB from the controller
C.
More specifically, if camera shake (deflections) in the X-direction
or the Y-direction, which is caused by hand shake, occurs upon a
camera shake correction switch SW (see FIG. 1) provided on the
camera body 12 is depressed (in an ON state), a gyro sensor GS
(deflection sensor; see FIG. 1) incorporated in the digital camera
10 detects the angular velocity in the X-direction and the angular
velocity in the Y-direction. Thereupon, based on data on these
angular velocities, the controller C calculates the moving distance
(amount of camera shake) in the X-direction and the moving distance
(amount of camera shake) in the Y-direction, and passes current
through at least one of the two X-direction drive coils CX and the
two Y-direction drive coil CYA and CYB. Thereupon, at least one of
the two X-direction drive coils CX and the two Y-direction drive
coil CYA and CYB generates a driving force in associated one of the
driving directions (FX1 or FX2, or FY1 or FY2) shown by the
thick-line arrows in FIG. 10 to move the image pickup device 44
(the stage plate 40) linearly in the X-direction or the Y-direction
relative to the camera body 12 in the direction opposite to the
direction of the camera shake by a moving distance identical to the
amount of the camera shake, and accordingly, the effects of shake
of the image pickup device 44 (image shake) that is caused by hand
shake or the like are compensated (corrected). Note that the moving
distances of the stage plate 40 in the X-direction and the
Y-direction are detected by the X-direction Hall element HX and the
two Y-direction Hall elements HY.
As described above, in the present embodiment of the shake
correction apparatus, portions of the leads 47 which are arranged
about the periphery of the image pickup device 44 and positioned in
front of the electrical board 45 face peripheral surfaces (outer
edges) of the two pairs of X-direction magnets MX and the two pairs
of Y-direction magnets MYA and MYB. However, since these peripheral
surfaces of the two pairs of X-direction magnets MX and the two
pairs of Y-direction magnets MYA and MYB are covered by the four
magnetic sheaths 35, 36 and 37, no magnetic force leaks from any of
these peripheral surfaces (or the amount of leakage of the magnetic
force is reduced significantly), which prevents magnetic forces
produced by the two pairs of X-direction magnets MX and the two
pairs of Y-direction magnets MYA and MYB from exerting an adverse
influence on the leads 47 in an effective manner.
Additionally, in the present embodiment of the shake correction
apparatus, magnetic forces produced by the two pairs of X-direction
magnets MX and the two pairs of Y-direction magnets MYA and MYB are
prevented from exerting an adverse influence on electronic devices
such as the aforementioned CPU that serves as the controller C
other than the image pickup device 44 in an effective manner since
the peripheral surfaces of the two pairs of X-direction magnets MX
and the two pairs of Y-direction magnets MYA and MYB are totally
surrounded and covered by the four magnetic sheaths 35, 36 and
37.
Additionally, magnetic forces produced by the two pairs of
X-direction magnets MX and the two pairs of Y-direction magnets MYA
and MYB are prevented from leaking outwards through the bottom of
the camera body 12 since the bottom surfaces of the two pairs of
Y-direction magnets MYA and MYB are covered by the two magnetic
sheaths 36 and 37, though being close to the bottom of the camera
body 12 as shown in FIG. 10. Therefore, even if an object A (see
FIG. 10) made of a magnetic substance comes near to the bottom of
the camera body 12 from the outside thereof as shown in FIG. 10,
there is no possibility of the object A being magnetically
attracted to the bottom of the camera body 12.
In addition, a problem with metal screws (not shown), for, e.g.,
fixing the shake correction apparatus 20 to the camera body 12,
being magnetically attracted to the bottom of the lower-end
connecting member 30 to thereby interfere with the operation
installing the shake correction apparatus 20 to the camera body 12
during this installing operation can be prevented from
occurring.
Although the present invention has been discussed with reference to
the above described embodiment of the shake correction apparatus,
the present invention is not limited solely to this particular
embodiment; making various modifications to the shake correction
apparatus is possible.
For instance, instead of providing the magnetic sheaths 35, 36 and
37, the peripheral surface of each pair of X-direction magnet MX
and the peripheral surface of each pair of Y-direction magnets MYA
and MYB can be plated with a magnetic substance (i.e., coated with
a layer of magnetic substance), e.g., electroless nickel plating
treated with heat at a high temperature, and leakage of magnetic
forces from the peripheral surfaces can be prevented by such a
plating or a layer of a magnetic substance.
In addition, the number of the retainers 32 and the number of the
balls B can be more than three.
Furthermore, it is possible that all the fitting holes 31 and the
retainers 32 be omitted so that the balls B are made to contact the
rear surface of the front stationary support board 21 to be allowed
to rotate. In this case, the diameters of the balls B are
determined to be slightly smaller than the distance between the
front stationary support board 21 and the rear stationary support
board 22 in the Z-direction.
Although the present invention has been applied to the above
described embodiment of the shake correction apparatus 20, in which
the stage plate 40 (and the electrical board 45) is rotatable, the
present invention can also be applied to a conventional shake
correction apparatus in which a stage plate and an electrical board
(which correspond to the stage plate 40 and the electrical board
45, respectively) move only linearly in the X-direction and the
Y-direction, and can even be applied to a stage apparatus used for
a different purpose other than the purpose of correcting image
shake (e.g., a stage apparatus in which a specific member is
movable linearly in the X-direction and the Y-direction or
rotatable).
Obvious changes may be made in the specific embodiment of the
present invention described herein, such modifications being within
the spirit and scope of the invention claimed. It is indicated that
all matter contained herein is illustrative and does not limit the
scope of the present invention.
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